Water pollution caused by a) oil spillages, b) leakage of organic hazardous material, c) water soluble dyes, d) weakly biodegradable organic material etc. is one of the major problems for the protection of the environment. Oil as well as many of the organic hazardous chemicals are hydrophobic (oleophilic) in nature and therefore float on the surface of the water. To selectively remove such oleophilic materials, it is desired to have a hydrophobic material, which can strongly adsorb these materials. A number of techniques have already been developed in the state of art to address the oil spillage problem such as (1) hydrophobic sponge, (2) metal meshes fabricated with fatty acid, spray dry process, solution immersion process etc, (3) metal substrate by wet chemical process, (4) membrane, containing self-assembly of co-polymer and polymeric LBL assembly, (5) filter paper, electrospum nanofiber (6) also with activated carbon, zeolites, clays, wool fiber etc.
In order to remove organic pollutants (dyes, Phenol, etc), which are soluble in water, it is required to have a material which can disperse in water. Generally used materials for this purpose include (1) semiconductor material which can photodegrade the organic pollutant in the presence of light, (2) high surface area carbon or carbon based composite, (3) Magnetic materials based high surface area composite, (4) Zeolites or porous silica etc.
Conventional materials used for the oil spillage problem (like sponge, meshes, different membrane, activated carbon, zeolites, clays, wool, fiber etc.) have some limitations such as environmental compatibility, low absorption capacity, and poor recyclability.
Activated carbon has collection problem due to very small particle size and also it has very high temperature regeneration problem. On the other side membranes are not suitable for the large area oil spillage problem and contamination removal from the surface of the water.
Therefore, it has been technologically very challenging to synthesize such materials which can be widely applied to the purification of both the above stated types of water purification issues.
There are reports in the literature on the synthesis of carbon-Fe3O4 composites.
An article titled “Superparamagnetic Nanocomposite of Magnetite and Activated Carbon for Removal of Dyes from Waste Water” by Pankaj Thakuria and Pattayil Alias Joy (NCL) in Nanoscience and Nanotechnology Letters Vol. 1, 171-175, 2009 report the synthesis of Fe3O4-AC nanocomposite at room temperature. According to the process disclosed in said article, dried powdered form of activated carbon black (Vulcan XC-72) was refluxed with 20% nitric acid and 20% sulfuric acid, Ar gas was purged through the mixture for 10 minutes before refluxing. The refluxed mixture was filtered and washed with distilled water several times and finally dried at 60° C. overnight to obtain modified carbon black. Fe3O4 nanoparticles were synthesized by the chemical co-precipitation method wherein FeSO4.7H2O and FeCl3.6H2O were taken in the 1:2 molar ratio and precipitated using 20% ammonia solution under argon atmosphere. Modified carbon black was then sonicated in distilled water for 10 minutes separately and added to the remaining precipitated solution and stirred. The pH of the solution was brought from 13 to neutral by slow addition of dil. HNO3 while stirring. The final product was isolated with a permanent magnet several times to wash out unattached carbon black.
An article titled “Synthesis and properties of magnetic Fe3O4-activated carbon nanocomposite particles for dye removal” by Yang; Na; Zhu; Shenmin; Zhang; Di; Xu et. al in Materials Letters, vol 62, issue 4-5, pgs 645-647 relate to magnetic Fe3O4-activated carbon nanocomposite synthesized from rice husk based activated carbon.
An article titled “Three-dimensionally macroporous Fe/C nanocomposites as highly selective oil-absorption materials” by Chu Y, Pan Q in ACS Appl Mater Interfaces. 2012 May; 4(5):2420-5 discloses three-dimensionally macro porous Fe/C nanocomposites synthesized by sintering a mixture of closely packed polystyrene micro spheres and ferric nitrate precursor.
Preparation and Supercapacitive Properties of Fe2O3/Active Carbon Nano composites” by LUO Pei-wen, YU Jian-guo et. al in Chem. Res. Chinese universities 2012, 28(5), 780-783 disclose synthesis of Fe2O3/AC nanocomposites. The process includes fabricating Fe2O3/AC nanocomposite by heating the Fe3+ impregnated AC in a N2 flow. Commercial activated carbon (AC) (Vulcan-32) was modified by HNO3 (63%, mass fraction) for 3 h at 80° C. to make it hydrophilic. This was followed by dispersing modified AC and Fe(NO3)3.9H2O in H2O. After vigorously stirring and ultrasonicating for 1 h, the mixture was filtered and dried. The dried filter residue was then heated at 750° C. for 3 h in a N2 flow to obtain the desired product.
These and all other extrinsic materials discussed herein are incorporated by reference in their entirety. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
However, the prior art methods do not disclose the preparation of Fe-based carbon composites with high surface area and high absorptive properties from the metal organic frameworks.
In view of the above, there is a need in the art to provide simple and scalable method of preparation Magnetic carbon composites with very high surface area starting from a Metal organic framework that can be widely applied to the purification of both the above stated types of water purification issues.